The purpose of this study has been to analyse the potential gender differences in the physical self-concept during the life span. The sample consisted of 1259 subjects: 627 adolescents (12-18 years old), 272 youths (19-30 years old), 248 adults (31-49 years old) and 112 elderly subjects (older than 55 years old) from the Basque Country. Research was conducted with a transversal design. The results show the existence of significant differences in favour of males during adolescence regarding Physical ability, Physical condition, Physical attraction, Strength, Physical self-concept and Self-concept scales; in Physical ability, Physical condition, Physical attractive, Strength and Physical self-concept in youths; and in Physical ability, Physical condition, Strength and Physical self-concept in adults. So males obtain better perceptions than the females in all the notable scales. Nevertheless, the analysis of the sizes of the effect and the selection of cases seems to indicate that the practice of physical activity might be the reason of the differences between men and women rather than the sex variable.